possibly fixed timing issue in test

Frameworks/MQTTnet.AspnetCore/MqttHostedServer.cs

@@ -11,8 +11,14 @@ namespace MQTTnet.AspNetCore
 {
     public class MqttHostedServer : MqttServer, IHostedService
     {
-        public MqttHostedServer(IOptions<MqttServerOptions> options, IEnumerable<IMqttServerAdapter> adapters, ILogger<MqttServer> logger, MqttClientSessionsManager clientSessionsManager) 
-            : base(options, adapters, logger, clientSessionsManager)
+        public MqttHostedServer(
+            IOptions<MqttServerOptions> options,
+            IEnumerable<IMqttServerAdapter> adapters,
+            ILogger<MqttServer> logger, 
+            MqttClientSessionsManager clientSessionsManager,
+            IMqttClientRetainedMessageManager clientRetainedMessageManager
+            ) 
+            : base(options, adapters, logger, clientSessionsManager, clientRetainedMessageManager)
         {
         }
 

Frameworks/MQTTnet.NetStandard/MqttFactory.cs

@@ -99,7 +99,9 @@ namespace MQTTnet
                 clientSessionsManager,
                 _serviceProvider.GetRequiredService<MqttClientSubscriptionsManager>(),
                 _serviceProvider.GetRequiredService<ILogger<MqttClientSession>>(),
-                _serviceProvider.GetRequiredService<ILogger<MqttClientPendingMessagesQueue>>());
+                _serviceProvider.GetRequiredService<ILogger<MqttClientPendingMessagesQueue>>(),
+                _serviceProvider.GetRequiredService<IMqttClientRetainedMessageManager>()
+                );
         }
 
         public IMqttClient CreateMqttClient()

Frameworks/MQTTnet.NetStandard/ServiceCollectionExtensions.cs

@@ -33,9 +33,9 @@ namespace MQTTnet
             services.AddTransient<IMqttServerAdapter, MqttServerAdapter>();
             services.AddTransient<IMqttPacketSerializer, MqttPacketSerializer>();
 
-            services.AddTransient<MqttClientSessionsManager>();
+            services.AddSingleton<MqttClientSessionsManager>();
             services.AddTransient<MqttClientSubscriptionsManager>();
-            services.AddTransient<MqttClientRetainedMessagesManager>();
+            services.AddSingleton<IMqttClientRetainedMessageManager, MqttClientRetainedMessagesManager>();
             return services;
         }